The invention relates to a transmission coil which is configured to inductively transfer energy, comprising a carrier, a coil arrangement with a multiplicity of turns, and a capacitance which forms, together with the coil arrangement, an oscillatory circuit. Further aspects of the invention relate to a fixed charging station and to a vehicle, each comprising such a transmission coil, and to a system for inductively charging vehicles comprising a fixed charging station and a vehicle.
Various systems for the contactless transfer of energy are known for conveniently charging electrical energy stores. Depending on the configuration, these systems can be used, for example, for charging consumer electronics such as, for example, cell phones or MP3 players or for charging electrically driven vehicles. Electrically driven vehicles comprise, for example, industrial trucks which are used for transporting goods in a warehouse, hybrid vehicles which have both an electric drive and an internal combustion engine, and purely electrically powered motor vehicles.
DE 20 2011 077 709 A1 discloses an arrangement for transmitting electrical energy, in particular for charging an energy store of a mobile carrier, in particular of a motor vehicle. The arrangement comprises an electromagnetic transmission unit which is formed by two transmission elements which are embodied as coils. One of the coils is assigned here to the motor vehicle, and the other is assigned to a charging station. Each coil is assigned a capacitor, wherein in each case a capacitor with a coil forms a resonant circuit. Furthermore, the arrangement comprises rectifiers, power inverters and a PFC (Power Factor Correction) circuit. The PFC circuit permits, inter alia, reactive power to be compensated. Using the reactive power compensation, it is also possible to transmit the energy with a high level of efficiency even in the case of a relatively weak inductive coupling.
A disadvantage of the prior art is that in addition to the transmission coils a multiplicity of separate components are also required.